Caster assemblies for moving articles, such as applications, furniture, and work-benches, and the like, are known. For example, West patent no. 165,965 discloses outside and inside bars which work upon each other through a pair of inclined slots, via a manual lever to raise or lower sewing machine casters.
Barltrop patent no. 2,152,946 discloses an attachment frame adapted to be secured to an article of furniture, including two longitudinal and two transverse bars; and a transverse equalizer bar having two springs connected between the opposite ends thereof and pivotable links and a tension member connected between the center of the equalizer bar and a fixed point. The springs continually urge four castors downwardly. The castors are brought into operation by upward force applied externally by the user, thereby neutralizing a part of the weight of the furniture.
Tilton patent no. 2,624,590 discloses a portable workstand having a system of pivotal links springs and levers for manually raising and lowering casters.
Geldhof patent no. 2,812,189 discloses a caster assembly for a washing machine, including front and rear pivotable links, interconnected at their upper ends by a tie link, with a spring connected between one of the pivotable links and the frame. Caster supporting shafts connected to the lower ends of the pivotable links are raised or lowered by an operating lever secured in either of two positions by a locking pin.
Lott patent no. 3,041,081 discloses a system of chair-supporting frame, links, brackets, and lever for manually raising and lowering four wheels.
Tucker et al patent no. 4,762,331 discloses a combination automobile seat and stroller including retractable wheels on a pivotally mounted frame actuated by a handle having an extension tab for selectively engaging upper or lower detents for respective raised and lowered positions.
Dooley patent no. 4,815,760 discloses an undercarriage arrangement for an article, such as a workbench, including a pair of wheels on pivotable arms adapted to being raised and lowered by a lever connected to one of the arms by a tension spring and rotatable through 180.degree..
Sanchas patent no. 4,828,281 discloses a child safety car seat having front and rear wheels connected to the seat by a pair of pivotally interconnected scissor links.
Kennel patent no. 4,872,693 discloses a combination infant car seat and stroller including a vertically movable central element connected at its ends to inner ends of respective extensions having wheels connected to the outer ends thereof, and adapted to pivoting the wheels inwardly and outwardly by raising and lowering the central element.
Clark patent no. 4,874,182 discloses an apparatus for converting a child's car seat into a mobile stroller unit, including two sets of each of front and rear linkage members operable by a central transverse drive rod controlled by an actuating lever and a cooperating latching mechanism.
Molnar patent no. 4,878,680 discloses a convertible car seat and stroller including a telescopic handle slidably mounted within supporting tubes to operate a cable arrangement for pivotally retracting and extending a wheel structure.
Qureshi et al patent no. 4,989,888 discloses a further combination child car seat and stroller, including pivotally mounted front and rear struts having front and rear wheels rotatably attached, and front and rear lock bars and associated cams having stepped lobes thereon for alternate engagement by the respective lock bards, with the struts and wheels moving to the their fully extended position by a combination of gravitational force and the force of a strut spring.